The Effects of Olanzapine Medication on Cognition in Patients with Schizophrenia

Kim, Chul Kwon; Byun, Won Tan; Choe, Byeong Moo

Abstract

OBJECTIVES
The purpose of this study is to examine differences of treatment responses and cognitive functions between typical antipsychotics and Olanzapine in schizophreniac inpatients.
METHODS
Ninety-nine patients with schizophrenia treated by Olanzapine (n=56) or typical antipsychotics (n=43) by their attending were included in this study. Prior to entering the study, all subjects did not take any antipsychotics for at least 4 weeks. Cognitive and psychopathological evaluations were carried out on three times: prior to drug assignment immediately after admission (baseline), 3 months and 6 months after starting medications. Cognitive assessments were blinded to medication and psychopathological status. Cognitive functions were examined for sustained attention, sensory register, executive function, concentration and attention, and verbal memory and learning using Degraded Stimulus Continuous Performance Test, Span Apprehension Task, Wisconsin Card Sorting Test, Digit Span, and Rey Auditory Verbal Learning Test.
RESULTS
The Olanzapine group presented a significantly greater improvement in the perseverative response, perseverative errors, number of completed categories of Wisconsin Card Sorting Test, forward Digit Span, immediate recall of Rey Auditory Verbal Learning Test, and positive and negative symptomatology than the typical antipsychotic group in the repeated-measures of ANCOVA among baseline, 3 month and 6 month assessments. These cognitive differences remained statistically significant after covarying out changes in symptomatology except forward Digit Span, which was affected by positive symptom in 3 month assessments.
CONCLUSION
These data suggest that Olanzapine is associated with significantly greater symptomatic improvement and less cognitive than typical antipsychotics, and its benefits continued after 3 and 6 months of treatment in patients with schizophrenia.